[Features of expression of the pertussis toxin operon under the control of its own and heterologous promotors in Bordetella bronchiseptica cells].

Expression of the cloned operon encoding the pertussis toxin synthesis under the control of operons own vir-dependent promoter or vir-independent promoter of Escherichia coli origin was studied. Proteins produced by the recombinant strains have been characterized. The pertussis toxin operon was shown to express under the control of both homologous and heterologous promoters in Bordetella bronchiseptica cells. Use of the lac-promoter increases the yield of produced toxin twofold. Copy number of operon in the cell does not influence the level of toxin production. The synthesized protein can be transported into the culture medium. The biological and physico-chemical properties of the protein are similar to the ones of the natural pertussis toxin. Bordetella bronchiseptica strain producing the toxin with decreased toxic activity has been obtained. Thus, a simple system for cellular expression of the toxin operon was constructed in Bordetella bronchiseptica. It permits one to construct new strains producing nontoxic derivatives of the pertussis toxin for construction of nonreactogenic vaccines.